#include <bits/stdc++.h> using namespace std; #ifdef LOCAL #include "debug.h" #else #define debug(...) 42 #endif long long dp[18][11][11]; string s; long long rec(int i, int j, int k, bool lower, bool valid) { if (i == 18) { return valid; } if (dp[i][j][k] != -1 && lower && valid) { return dp[i][j][k]; } int m = lower ? 9 : s[i] - '0'; long long res = 0; for (int c = 0; c <= m; ++c) { if (c ^ j && c ^ k) { bool lo = lower || c < m, ok = valid || c; res += rec(i + 1, ok ? c : 10, j, lo, ok); } } return lower && valid ? dp[i][j][k] = res : res; } long long calc(long long x) { if (x < 0) { return x; } s = to_string(x); while (s.size() < 18) { s = '0' + s; } return rec(0, 10, 10, 0, 0); } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); long long a, b; cin >> a >> b; memset(dp, -1, sizeof(dp)); cout << calc(b) - calc(a - 1); return 0; }